Magnesium oxide has properties of being inexpensive and chemically stable, exhibiting basicity, and having non-toxicity. Thus, this substance is used as various applications, examples of which include an adsorbent for adsorbing unpleasant odor generated when an ABS-based resin is shaped or processed (for example, Patent Document 1), an acid acceptor for waste plastics (for example, Patent Document 2), and a scorch retarder for preventing over-crosslinkage of a rubber such as chloroprene rubber (for example, Non-Patent Document 1).